Be especially cautious when filling fuel cans during summer;
static buildup can cause fires while fueling

By Peter D. duPre

Filling a portable gasoline can at a service station is something most of us
do dozens of times each summer, whenever the lawn mower, chain saw or ATV runs
low on gas. In fact, it happens so frequently that we don't even think about
it. According to safety experts at Chevron Corporation, however, we should think
about it. They warn there is a potential risk of fire due to static electricity
buildup when filling a portable container -- especially if the fuel can is left
in the trunk of a car or the back of a pickup.

Despite the potential for tragedy, gasoline fires caused by static electricity
are rare. Only 24 fires and 5 injuries during the past few years have been reported
due to improper fueling of portable cans. When you consider that millions
of gasoline cans are filled at pumps every year, these figures don't make it
seem like much of a problem -- unless it happens to you.

Gasoline, by its very nature, is extremely volatile. We’ve all seen the explosive
fumes rising from the fuel filler on a hot day, and there is always a danger
of a fire when fueling any vehicle or filling a container. That is why filling
stations have signs out by the pumps that tell you not to smoke and to turn
off the engine. Still, as dangerous as fill-ups can be, fires caused by static
electrical build up while filling a vehicle are so rare because both the vehicles
and the pumps are designed to dissipate the static electricity to the ground.
Your vehicle may not appear to be grounded, but Chevron's safety engineers say
the tires are good enough conductors to allow electrical discharge to escape
to ground under normal conditions.

An approved gasoline container also dissipates static electricity, as long as
it is placed on the pavement before filling begins. Leave the can in the trunk
or pickup box, however, and it is a different story. A trunk liner, bed mat
or bed liner insulates the vehicle from the ground and the static buildup of
electricity has nowhere to go. Static buildup occurs and if it releases, the
resulting spark can set off the gasoline.

The static comes from the gasoline itself. As the fuel flows through the hose
and nozzle, static electricity builds up on the gasoline. This charge takes
several seconds to dissipate after the gas is poured into the can. If the can
is insulated from ground, the spark cannot dissipate and it builds up until
discharge occurs.

According to Chevron, the condition most likely to lead to spark discharge is
the filling of a metal container that is placed upon the plastic bedliner of
a pickup. In their experiments, this situation resulted in the most fires. They
are also quick to point out that while static discharge in metal containers
caused the most fires, plastic containers are not immune.

Use only approved and
properly labeled gasoline containers. The gas can should be red in color and
have a Underwriter's Laboratories (UL) or the American Society for Testing
and Materials (ASTM) stamp on them.

Place the container on
the ground before filling to allow static buildup to dissipate. Make sure
the filler nozzle touches the rim of the filler opening to help static electricity
dissipate.

Fill the container only
95 percent full. Leave an air space so the fuel can expand as temperatures
increase.

Always fill the can manually;
never use the trigger lock on the nozzle.

Turn off your car's motor
before fueling and extinguish any cigarettes or open flames.